Broncolor Transmitter/Receiver RFS 2.1 Kit. The kit consists of two basic units (transmitter and receiver), an extensive set of cables and an USB current supplier (incl. rechargeable batteries). With the transmitter/receiver kit it is possible to trigger any number of studio flash units from the camera. Powered by a single 3V CR2450 battery, optional USB power supply input for battery-less operation. Specifications Studio address setting range: 1-99 Operational distance in open air: up to 200 m